Benzodiazepine, (BZP) ,derivatives represented by diazepam have been use for a long as an antianxiety drug or a therapeutic medicine for sleep disturbance. The recent pharmacological studies have shown that there exist receptors which exhibit a specific affinity for BZP derivatives in the central nervous system [Science, vol. 198, 849 (1977)]. In the studies and researches conducted subsequently, there have been investigated and developed not only BZP derivatives but also compounds which have structures different from BZP but exhibit a high affinity for BZP receptors and a BZP-like action (BZP agonist), compounds which exhibit a high affinity for BZP receptors but exhibit a pharmacological action the reverse of BZP (BZP inverse agonist), and compounds which exhibit a high affinity for BZP receptors but nevertheless exhibit no pharmacological activity themselves and rather show an antagonistic action against the action of the agonist or the inverse-agonist (BZP antagonist) [Advance in Drug Research, vol. 14, 165 (1985)].
Since BZP derivatives which are used as an antianxiety drug have a sedative action, a muscle-relaxing action and an anticonvulsive action in addition to an antianxiety action, they often cause troubles in terms of side effects such as dizziness and sleepiness. Thus, researches of non-BZP types of compounds aiming at developing selective antianxiety drugs with less side effects are thriving. Nevertheless, there have not been found satisfactory ones yet.
Also, in recent years, amnesia-inducing actions by BZP agonists were found [Nature, vol. 321, 864 (1986)], and there have been reports suggesting the possibility that BZP-antagonists exhibiting an antagonistic action against the amnesic actions induced by BZP agonists, and BZP-inverse-agonists exhibiting an action reverse to the amnesic actions by BZP agonists, are usable as brain-function activating drugs. [Trends in Neurosciences, vol. 11, 13 (1988)].
In the meantime, in the specification of U.S. Pat. No. 4,602,019 there are disclosed compounds such as 2,4,4a,5-tetrahydro-7 -(1H-imidazol-1-yl)-3H-indeno[1,2-c]pyridazin-3-one having a cardiac action and an antihypertensive action. The Journal of Medicinal Chemistry, vol. 24, 830 (1981) discloses compounds such as 2-(4-chlorophenyl)benzothiopyrano-[4,3-c]pyrazol-3-one possessing an immune-supressing action.